In recent times, there have been considerable investigations of alternative fuel sources to those derived from petroleum crude. One such area of investigation has included alcohols and certain organic acids such as butyric acid. Butyric acid and normal butanol are potential fuel sources available from fermentation of carbohydrate containing industrial materials such as municipal solid waste, waste paper, distressed grain, agricultural crop residue such as corn cobs and the like, and other such fermentation substrates. For example, butanol fermentation takes place in the presence of butanol forming bacterium such as Clostridium acetobutylicum (Weizmann). This invention relates to the use of aqueous microbial fermentation broths which contain small percentages of butyric acid and butanol. The primary objective of the invention is to extract the butyric acid and butanol from the microbial fermentation broth in an efficient energy manner.
Such fermentation broths may typically contain from about 0.2% up to about 1% by weight of each of normal butyric acid and normal butanol. For effective and efficient use, the butyric acid and butanol must be extracted and concentrated. It goes without saying that the extraction and the concentration must be in a manner which is efficient and itself not high energy consuming. For example, if tremendous amounts of energy are consumed in the extraction any energy efficiency from the alternative fuel source is simply consumed in the preparation, making the net balance negative. Thus, it is not feasible to employ a process which is highly efficient for separation purposes, but one which uses an amount of energy at least equal to or greater than the amount of energy theoretically available from the extracted butyric acid and/or butanol.
This invention has as its primary objective a means of efficiently and in a low energy manner, extracting butyric acid and butanol from microbial fermentation broths.
Another objective of the present invention is to efficiently and in a low energy manner extract butyric acid and butanol from microbial fermentation broths by use of vinyl bromide as the extracting solvent.
Another objective of the present invention is to provide a highly efficient extraction unit operation for maximizing the efficiency of vinyl bromide extraction of butyric acid and butanol from aqueous fermentation broth.
A yet further objective of the present invention is to provide an efficient and cost effective process utilizing vinyl bromide in a column extraction process for the recovery of butyric acid and normal butanol from microbial fermentation systems.
A yet further objective of the present invention is to develop an extraction system for extracting butyric acid and normal butanol from microbial fermentation broths which is far superior and more efficient than the extraction of butanol from such broths by use of Freon 11 as disclosed in Levy, U.S. Pat. No. 4,260,836, issued Apr. 7, 1981.
The means and manner of accomplishing each of the above objectives as well as others, will become apparent from the detailed description of the invention which follows hereinafter.